LHCD current profile control experiments towards steady state improved confinement on JT-60U

Ide, S.; Naito, O.; Oikawa, T.; Fujita, T.; Kondoh, T.; Seki, Masanori; Ushigusa, K.; Team, Jt

doi:10.1088/0029-5515/40/3y/302

Cited by 61 publications

(61 citation statements)

References 15 publications

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“…Figure 11 summarizes various JT-60U discharge regimes on the H 89P and n e /n GW . The highest normalized density with high confinement has been achieved by the RS discharges produced by LHCD (+ NB injection) [41]. In this regime, H 89P >2 has been achieved at a very high value of n e~ 1.15 n GW .…”

Section: Extension Of High Confinement Regime Towards High Densitymentioning

confidence: 95%

Profile and Shape Control of the Plasmas with Transport Barriers towards the Sustainment of High Integrated Performance in JT-60U.

Kamada¹

2002

J. Plasma Fusion Res.

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With the main aim of providing physics basis for ITER and the steady-state tokamak reactor, JT-60U has been optimizing the operational concepts and extending discharge regimes toward the sustainment of high integrated performance. In the two advanced operation regimes, the reversed magnetic shear (RS) and the weak magnetic shear (high-β p ) ELMy H modes characterized by both internal (ITB) and edge (ETB) transport barriers, JT-60U has clarified responses of the transport barrier structure to magnetic shear, heating power, momentum, density, etc. Based on these observations, possible parameter linkages and feedback loops in the core and pedestal regimes have been proposed. With the optimization of profile and shape control, both confinement and high β stability have been enhanced and favorable integrated performance has been achieved. Such operational regimes have been extended to the reactor-relevant regime.

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Section: Extension Of High Confinement Regime Towards High Densitymentioning

confidence: 95%

Profile and Shape Control of the Plasmas with Transport Barriers towards the Sustainment of High Integrated Performance in JT-60U.

Kamada¹

2002

J. Plasma Fusion Res.

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“…6 Finally, hollow current profiles can improve wall stabilization of low-n kink modes. 7 Such operational modes have been produced on DIII-D, 8 JET, 9 JT-60U, 10 ASDEXUpgrade, 11 and C-Mod 12 and are important components for future ITER scenario planning. 13 However, off-axis minimum q-profiles provide conditions that are favorable to the existence of energetic particle driven reversed shear Alfv en eigenmode (RSAE) instabilities.…”

Section: Introductionmentioning

confidence: 99%

Verification and validation of linear gyrokinetic simulation of Alfvén eigenmodes in the DIII-D tokamak

et al. 2012

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A verification and validation study is carried out for a sequence of reversed shear Alfv en instability time slices. The mode frequency increases in time as the minimum (q min ) in the safety factor profile decreases. Profiles and equilibria are based upon reconstructions of DIII-D discharge (#142111) in which many such frequency up-sweeping modes were observed. Calculations of the frequency and mode structure evolution from two gyrokinetic codes, GTC and GYRO, and a gyro-Landau fluid code TAEFL are compared. The experimental mode structure of the instability was measured using time-resolved two-dimensional electron cyclotron emission imaging. The three models reproduce the frequency upsweep event within 610% of each other, and the average of the code predictions is within 68% of the measurements; growth rates are predicted that are consistent with the observed spectral line widths. The mode structures qualitatively agree with respect to radial location and width, dominant poloidal mode number, ballooning structure, and the up-down asymmetry, with some remaining differences in the details. Such similarities and differences between the predictions of the different models and the experimental results are a valuable part of the verification/validation process and help to guide future development of the modeling efforts.

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“…Since the q-profile and magnetic shear are largely determined by the bootstrap current [9] in a high-performance non-inductive discharge, a non-linear link exists between the profiles of pressure, current and χ, which can lead to self-organized, improved confinement [10,11]. Experimentally [12,13], the most direct method of controlling the ITB is to modify the current profile by changing the frequency and phasing of the ECCD or LHCD sources and by modulating the NB-injection energies. Besides these direct control methods, active control of the ITB strength was demonstrated by varying the amount of toroidal momentum injected by the NBs [14].…”

Section: Introductionmentioning

confidence: 99%

Direct Observation of Molecular Orbital at Carbon Nanotube End

Furuhashi

Komeda

2007

jjap

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A self-consistent simulation, including a model for improved core energy confinement, demonstrates that externally applied, inductive current perturbations can be used to control both the location and strength of internal transport barriers (ITBs) in a fully non-inductive tokamak discharge. We find that ITB structures formed with broad non-inductive current sources such as LHCD are more readily controlled than those formed by localized sources such as ECCD. Through this external control of the magnetic shear profile, we can maintain the ITB strength which is otherwise prone to deteriorate when the bootstrap current increases. The inductive current perturbation, which can be implemented by a weak Ohmic power, offers steady-state, advanced tokamak reactors an external means of efficient ITB control for regulating the fusion-burn net output and spatial profile.

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LHCD current profile control experiments towards steady state improved confinement on JT-60U

Cited by 61 publications

References 15 publications

Profile and Shape Control of the Plasmas with Transport Barriers towards the Sustainment of High Integrated Performance in JT-60U.

Profile and Shape Control of the Plasmas with Transport Barriers towards the Sustainment of High Integrated Performance in JT-60U.

Verification and validation of linear gyrokinetic simulation of Alfvén eigenmodes in the DIII-D tokamak

Direct Observation of Molecular Orbital at Carbon Nanotube End

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